Example embodiments of the present disclosure relate to a particle counting device and/or an exposure system with the same, and in particular, to a particle counter configured to distinguish particles from bubbles in fluid and/or an immersion exposure system having the same.
Conventionally, the formation of a semiconductor device includes a plurality of unit processes, such as a thin-film deposition process, a photolithography process, and an etching process. To form a photoresist pattern serving as an etch mask on a wafer or a thin layer, the photolithography process includes a photoresist coating process, an exposure process, and a developing process. The exposure process is performed to selectively expose a photoresist layer with ultraviolet light using a photomask or a reticle, and the developing process is performed to selectively remove one of exposed or non-exposed portions of the photoresist layer.
A critical dimension (CD) of a semiconductor device may be decided by an exposure system to be used for the exposure process. A density of the semiconductor device may be inversely proportional to a wavelength of an exposure light to be used in the exposure process. In the past, a G- or I-line had been used for the exposure light, but KrF or ArF is recently being used for the exposure light. Although the ArF light has the minimum wavelength that can be achieved from the commercialized light sources for the exposure process, the usage of an immersion exposure system makes it possible to use an ultraviolet light, whose wavelength is shorter than that of the ArF light. In the immersion exposure system, the water, whose refractive index is higher than that of the air, is interposed between an object lens and a wafer of ArF exposure system, and thus, a light with shorter wavelength can be used for the exposure process.